Cognate with Latvian usna (“thistle”) and probably with dialectal Proto-Slavic *ušь (“carduoid”) (whence Old East Slavic оушь (ušĭ)), for Proto-Balto-Slavic [Term?] (“thistle”). Further origin uncertain. Possibly derived from the oblique ablaut-grade of Proto-Indo-European *wósHr̥ ~ *usHén-, whence Sanskrit उष्ण (uṣṇa, “onion”), Latin ūniō (“onion”).